This invention relates generally to inflation devices used in medical procedures, and more particularly, to an automated manifold control system suitable for controlling the expansion and deflation of catheter balloons used in procedures within a body lumen such as a blood vessel and for controlling the delivery of desired components to the body lumen that is the subject of the procedure. Such procedures include, for example, vascular procedures such as angioplasty or restoring patency of a blood vessel.
Dilatation balloon catheters have been used in increasing numbers in angioplasty procedures to dilate or enlarge body lumens such as blood vessels that have been partially or almost completely blocked by stenosis. In addition to vascular procedures such as dilatation of the coronary and peripheral arteries, angioplasty procedures have been used to treat stenoses and other lumens, such as urethral passages and fallopian tubes. Particularly, the procedure for dilating coronary arteries, referred to as percutaneous transluminal coronary angioplasty (PTCA), has provided an effective and less traumatic treatment technique than coronary by-pass surgery or other surgical treatment methods.
In a typical angioplasty procedure, a guiding catheter is percutaneously introduced into the vascular system of a patient and is directed to a point near the site of the stenosis. Subsequently, a guidewire and a dilatation catheter having an inflatable balloon on the distal end thereof are introduced through the guiding catheter with the guidewire slidably disposed within an inner lumen of the dilatation catheter. The guidewire is advanced out of the distal end of the guiding catheter and is maneuvered into the patient's vasculature containing the stenosis to be dilated, and is then advanced beyond the stenosis. Thereafter, the dilatation catheter is advanced over the guidewire until the dilatation balloon is located across the stenosis.
Once in position across the stenosis, the balloon of the dilatation catheter is filled with radiopaque liquid at relatively high pressures and is inflated to a predetermined size, preferably the same as in the inner diameter of the artery at that location. The inflated balloon radially compresses the atherosclerotic plaque and/or other deposits comprising the stenosis against the inside of the artery wall to thereby dilate the lumen of the artery and allow blood to flow freely therethrough. In a typical procedure, the balloon is expanded and deflated several times, with the pressure maintained for several seconds during each expansion, until the desired patency in the blood vessel is obtained. To determine whether the desired patency of the blood vessel is obtained, it may be desirable to deliver radiopaque liquid to the repaired site so that, through the use of radiography, the interior profile of the blood vessel can be viewed. It may also be desirable to flush the site with some solution to facilitate a complete repair of the blood vessel or to deliver drugs into the blood vessel. Once the desired patency is obtained and any desired components have been delivered to the blood vessel, the dilatation catheter can be removed.
To expand or deflate the balloon, the physician typically uses a system such as a syringe connected to the catheter and in fluid communication with a lumen leading to the interior of the balloon. The physician uses one hand to grasp the syringe body and the other hand to actuate the plunger to pressurize and depressurize the expansion fluid. Similarly, to deliver a desired component into the blood vessel, a syringe may be connected to the catheter and in fluid communication with a second lumen that is in turn in fluid communication with the interior of the blood vessel. Here also, the physician uses one hand to grasp the syringe body and the other hand to actuate the plunger to deliver the desired component into the blood vessel.
There are some drawbacks associated with manual inflation procedures such as the ones described. For example, each time the physician wants to adjust or change the location of the balloon in the artery she must use her hand alternatingly on the proximal end of the catheter for maneuvering the balloon to the desired location, and on the component delivery device or the expansion device for pressurizing or depressurizing the balloon. Rather than switching hands between the balloon catheter and the delivery or expansion device, it is desirable for the physician to be able to simultaneously control the component delivery or expansion pressure and the location of the balloon in the artery. This simultaneous control of position and component delivery or balloon expansion pressure is not possible for a single physician using present manual procedures. Another drawback of manual systems is that the physician may experience hand fatigue as a result of operating a delivery or expansion device for several cycles, each lasting several seconds, during an angioplasty procedure. Additionally, manual inflation devices are typically bulky than when compared with more fragile and delicate dilatation balloon catheters and the presence of such a bulky instrument is preferably to be avoided in the immediate area of an angioplasty procedure.
In recent years, automated devices have become known, including microprocessor controlled units wherein a microprocessor provides control signals to a drive unit which advances or retracts a syringe for purpose of expanding or deflating a balloon catheter. The drive unit can be made to follow a predetermined pressure output pattern, based on the pressure detected by a pressure transducer in fluid communication with the radiopaque expansion media, and an internal clock.
However, these conventional automated devices have limitations. First of all, the prior art automated devices generally do not incorporate a scheme for automatically or semi-automatically controlling delivery of desired components into the blood vessels being repaired. In addition, they do not take into account variations in individual catheter volume, nor do they take into consideration system compliance or individual catheter compliance characteristics. Another problem with prior art automated devices is that expansion times and pressure are generally not controlled by the physician as treatment is taking place.
What has been needed and heretofore unavailable is an automated system that frees the physician from difficulties of manual component delivery and balloon expansion and deflation, but accounts for individual differences in balloon catheters and provides feedback to the physician regarding component delivery and expansion/deflation. The present invention fulfills this need.